app/django/utils/simplejson/scanner.py
author Pawel Solyga <Pawel.Solyga@gmail.com>
Sun, 19 Oct 2008 21:12:08 +0000
changeset 394 4c60652a3947
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Add BaseForm class to soc.views.helper.forms module (work in progress). This changes the way as_table function displays the form (for more information have a look into doc string). BaseForm is going to be used for all forms in Melange in future. Right now it's still missing custom form errors labels and "required" text in 3rd column, but that's added as TODO and I'm working on it. Patch by: Pawel Solyga Review by: to-be-reviewed

"""
Iterator based sre token scanner
"""
import re
from re import VERBOSE, MULTILINE, DOTALL
import sre_parse
import sre_compile
import sre_constants
from sre_constants import BRANCH, SUBPATTERN

__all__ = ['Scanner', 'pattern']

FLAGS = (VERBOSE | MULTILINE | DOTALL)

class Scanner(object):
    def __init__(self, lexicon, flags=FLAGS):
        self.actions = [None]
        # Combine phrases into a compound pattern
        s = sre_parse.Pattern()
        s.flags = flags
        p = []
        for idx, token in enumerate(lexicon):
            phrase = token.pattern
            try:
                subpattern = sre_parse.SubPattern(s,
                    [(SUBPATTERN, (idx + 1, sre_parse.parse(phrase, flags)))])
            except sre_constants.error:
                raise
            p.append(subpattern)
            self.actions.append(token)

        s.groups = len(p) + 1 # NOTE(guido): Added to make SRE validation work
        p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
        self.scanner = sre_compile.compile(p)

    def iterscan(self, string, idx=0, context=None):
        """
        Yield match, end_idx for each match
        """
        match = self.scanner.scanner(string, idx).match
        actions = self.actions
        lastend = idx
        end = len(string)
        while True:
            m = match()
            if m is None:
                break
            matchbegin, matchend = m.span()
            if lastend == matchend:
                break
            action = actions[m.lastindex]
            if action is not None:
                rval, next_pos = action(m, context)
                if next_pos is not None and next_pos != matchend:
                    # "fast forward" the scanner
                    matchend = next_pos
                    match = self.scanner.scanner(string, matchend).match
                yield rval, matchend
            lastend = matchend


def pattern(pattern, flags=FLAGS):
    def decorator(fn):
        fn.pattern = pattern
        fn.regex = re.compile(pattern, flags)
        return fn
    return decorator